Plug in disconnects



Dec. 15, 1959 F. E. CHABOT 2,917,612

PLUG IN DISCONNECTS Filed Nov. 25, 1957 United States PLUG INDISCONNECTS Application November 25, 1957, Serial No. 698,832 4 Claims.(Cl. 200-166) This invention relates to a novel disconnect jaw formaking connection to a cooperating current carrying member, and morespecifically relates to a disconnect jaw having a plurality of fingershaving different lengths whereby current paths from the cooperatingmember to the contacting fingers are non-coincident and the currentdensity and thermal flow pattern are distributed over a relatively largearea at the contacting area,

Disconnect jaws as used in blade switches or plug-in disconnection meansfor panel-board circuit breakers are well known in the art and areusually comprised of a flat bus or blade which cooperates with a jaw ofa single sheet of conductive material or a plurality of fingers eachhaving the same length. Because of this construction, the contact areaalongthe full length of the disconnect jaw is at substantially the sametransverse position whereby current flow across the contact area fromthe switch blade to the jaw is concentrated at this transverse sectionof the jaw. Thus, there will be a high concentration of current densityat this relatively thin area of contact engagement between the jaw andthe blade which leads to a distorted thermal fiow pattern withsubsequent generation of heat and higher electrical resistance at thecontact. At the same time, a relatively high plug-in force is requiredsince the blade is simultaneously connected to the current carryingportions of the jaw, which portions are biased into engagement with theblade so as to achieve good electrical contact.

The object of my invention is to provide a novel disconnect jaw in whichthere is a broad distribution of current density and hence a betterthermal flow pattern at the point between the connection between a bladeand a disconnect jaw.

Another object of my invention is to provide a novel disconnect jawwhich has a relatively low contact resistance.

Another object of the invention is to provide a novel disconnect jawwhich includes contacting fingers which are staggered.

A further object of my invention is to provide a novel disconnect jawhaving a plurality of fingers of different lengths for engaging acooperating conductor in a staggered manner to thereby improve thethermal flow pattern at the contact area.

These and other objects of my invention will become apparent from thefollowing description when taken in connection with the drawings, inwhich:

Figure 1 shows a disconnect switch having a disconnect jaw constructedin accordance with my invention.

Figure 2 is a top view of the disconnect switch of Figure 1.

Figure 3 is a perspective view of my novel disconnect aw.

Figure 4 is an enlarged view of the disconnect jaw portion of Figure 1.

Figure 5 is a sectional view of Figure 4 taken across the lines 5-5.

Referring now to Figure 1, the disconnect switch shown atent therein iscomprised of a base 10 which supports insulator members 12 and 14.Insulator members 12 and 14 then support terminal cars 16 and 18respectively which are fastened thereto in any desired manner as by boltmeans 13 and 15.

Terminal 18 has a pair of upwardly protruding arms 20 and 22 (Figure 2)which pivotally support switch blade 24 by means of the pivot pin 25which extends through cooperating apertures in arms 20 and 22. It is tobe noted that a current connection is completed from switch blade 24through arms 20 and 22 to the end of terminal member 18 in anyconventional desired manner.

The left-hand end of blade 24 is then seen in Figure 1 as being inengagement with my novel disconnect jaw 26 which is fastened to terminalcar 16 by bolt means 28 and 30, or in any desired manner, and blade 24may be moved into and out of engagement with disconnect jaw 26 by aforce applied to pull-ring 32 which is fastened to blade 24. Thus, whenthe blade 24 engages disconnect jaw 26 a current path is completed fromterminal 16, disconnect jaw 26, blade 24, arms 20 and 22, and terminal18.

In order to open this current path, it is only necessary to apply aforce to pull-ring 32 which will rotate blade 24 in a clockwisedirection about pivot pin 25,whereby blade 24 moves out of engagementwith jaw 26.

My novel disconnect jaw 26 is best seen inFigure 3 as comprising a firstplurality of fingers 34, 36, 38 and 40, and a second plurality offingers 42, 44, 46 and 48 which may be formed of a unitary sheet ofconductive material bent into a U-shape, as shown in Figure 3.

Each of fingers 34 through 48 are tied to a common member formed by thebottom portion 50 of the U-shaped material in Figure 3. However, it isto be noted that in accordance with my invention, it is only necessarythat a plurality of fingers having different lengths be provided andthat they may be formed of physically separate members which are onlyultimately fastened at some current connecting point.

Each of fingers 34 through 40 of the first plurality of contactingfingers are seen in Figure 3 to be progressively longer, while thecontact fingers 42 through 48 which are aligned with fingers 34 through40 are progressively shorter. gered in a first direction, while fingers42 through 48 are staggered in a second direction.

It is to be further noted that the upper contacting portions of each ofthe fingers of Figure 3 are bent inwardly so as to afford an area ofhigh pressure contact with respect to an interposed blade.

Figures 4 and 5 show the use of the disconnect jaw 26 of Figure 3 in theembodiment of Figure 1 in an enlarged view to specifically show themanner in which current distribution at the contacting area is spreadover a large area. In the normal type of disconnect jaw, the contactingportion of each of fingers 34 through 48 will be longitudinally alignedwhereby current flowing through blade 24 will be concentrated along thatline and thus cause an increased current density and a distorted thermaldistribution. In the case of Figure 3, however, the current flow inblade 24 is comprised of distinct paths to each respective finger, thesepaths being non-overlapping.

That is to say, there will be a first current path to finger 34 from thelower portion of blade 24; a second current path will be formed from alower intermediate portion of blade 24 to finger 36; a third currentpath will be from the higher intermediate portion of blade 24 to finger38, while a fourth path will be in the upper portion of blade 24 to thefinger 40.

Thus, since the fingers are of different transverse dimensions, theblade 24 will carry longitudinally displaced currents to the individualfingers whereby the current That is to say,- fingers 34 through 40 arestag;

density of the blade is spread out throughout the complete blade andthermal distribution will be substantially the same as for normalcurrent flow through the blade. Because of this, the area will runcooler and contact resistance will be lower.

In order to further stagger the current path, the fingers 42 through 48on the other side of blade 24 are staggered in an opposite direction, asshown in Figures 3, 4 and 5. This causes'a still further improvement inthermal characteristics of the blade since the fingers which oppose oneanother, such as fingers 4t) and 4? will contact the blade atlongitudinally displaced portions and thus avoid a concentration ofheating at any one point along the blade.

While the embodiment set forth herein has been specifically directed tothe use of my novel disconnect jaw in a disconnect switch, it is to beclearly noted that the disconnect jaw is not limited to thisapplication.

By way of example, in a plug-in type of circuit breaker or panel-boardcircuit breaker, the circuit breaker terminals may be adapted to; be ofthe blade type and coopcrate with a jaw terminal of the type set forthin Figure 3 which is'fastened to the panel-board.

Although I have described preferred embodiments of my novel invention,many variations and modifications will now be obvious to those skilledin the art, and I prefer therefore to be limited not by the specificdisclosure herein but only by the appended claims.

I claim:

1. A disconnect jaw for making a current connection to a cooperatingconductor; said disconnect jaw having a first plurality of contactingfingers extending from a common member and being adapted to be biasedinto engagement with one side of said cooperating conductor and a secondplurality of contacting fingers extending from a common member and beingadapted to be biased into engagement with another side of said coopfroma common member and being adapted to be biased into engagement withanother side of said cooperating conductor; the fingers of said firstplurality of fingers having different lengths to be staggered in a firstdirection; the fingers of said second plurality of fingers havingdifferent heights to be staggered in an opposite direction; each of saidfingers of said first and second plurality of fingers formingnon-coincident current paths from said cooperating conductor to saidfingers.

3. In a disconnect jaw for electrically cooperatingwith a movable blade;said disconnect jaw comprising a first and second plurality of extendingfingers adapted to engage opposite sides of said movable blade inlongitudinal alignment with one another when said movable lade is movedin a first plane'into engagement with said disconnect jaw; the engagingportion of each finger of each of said first and second plurality offingers W respectively being transversely displaced when measured insaid first plane, with respect to said fingers of the correspondingplurality of fingers; the engaging portions of the fingers alignedopposite one another in each of said first and second plurality offingers being transversely misaligned with respect to one another.

4. In a disconnect jaw.for electrically cooperating with a movableblade; said disconnect jaw comprising a first and 'second plurality ofextending fingers adapted to engage opposite sides of said movable bladein longitudinal alignment with one another when said movable blade ismoved in a first plane into engagement with said disconnect jaw; theengaging portion of each finger of each of said first and secondplurality of fingers respectively being transversely displaced whenmeasured in said first plane, with respect to said fingers of thecrating conductor; the fingers of said first plurality cooperatingconductor; the fingers of said first plurality of fingers havingdifierent lengths to be staggered in a first direction; the fingers ofsaid second plurality of fingers having different heights to bestaggered in an opposite direction.

2. A disconnect jaw for making a current connection to a cooperatingconductor; said disconnect jaw having a first plurality of contactingfingers extending from a common member and being adapted to be biasedinto engagement with one side of said cooperating conductor and a secondplurality of contacting'fingers extending corresponding plurality offingers; the engaging por-,

tions of the fingers aligned opposite one another in each of said firstand second plurality of fingers being transversely misaligned withrespect to one another; said plurality of fingers engaging said blade ina staggering.

' relationship thereby equally distributing current density and thermalflow at the junction portion between said blade and said disconnect jaw.

References Cited in the file of this patent UNlTED STATES PATENTS1,477,527 Raettig Dec. 11, 1923 1,957,213 Hobson May l, 1934 2,765,380Graybill Oct. 2, 1956 2,789,189 Graybill et al. Apr. 16, I957

